In order to meet the demand for wireless data traffic soaring since the 4th generation (4G) communication system came to the market, there are ongoing efforts to develop enhanced 5th generation (5G) communication systems or pre-5G communication systems. For the reasons, the 5G communication system or pre-5G communication system is called the beyond 4G network communication system or post LTE system.
For higher data transmit rates, 5G communication systems are considered to be implemented on ultra-high frequency bands (mmWave), such as, e.g., 60 GHz. To mitigate pathloss on the ultra-high frequency band and increase the reach of radio waves, the following techniques are taken into account for the 5G communication system: beamforming, massive multi-input multi-output (MIMO), full dimensional MIMO (FD-MIMO), array antenna, analog beamforming, and large scale antenna.
Also being developed are various technologies for the 5G communication system to have an enhanced network, such as evolved or advanced small cell, cloud radio access network (cloud RAN), ultra-dense network, device-to-device (D2D) communication, wireless backhaul, moving network, cooperative communication, coordinated multi-point (CoMP), and interference cancellation.
There are also other various schemes under development for the 5G system including, e.g., hybrid FSK and QAM modulation (FQAM) and sliding window superposition coding (SWSC), which are advanced coding modulation (ACM) schemes, and filter bank multi-carrier (FBMC), non-orthogonal multiple access (NOMA) and sparse code multiple access (SCMA), which are advanced access schemes.
Various schemes are being put forward in preparation for providing stable communication services considering communication environments in wireless communication systems. For example, a wireless communication system may carry out congestion control in order to achieve high performance and avoid collapse due to congestion.
As an example, the transmission control protocol (TCP) adopts two mechanisms, i.e., flow control and congestion control, to ensure end-to-end reliability.
Flow control is to control the amount of packets that the transmit device is to send considering the status of the receive buffer of the receive device, and congestion control is to adjust the amount of packets that the transmit device is to send considering network congestion (e.g., the status of the buffer of a relay device).
The transmit device may perform flow control by receiving an advertised window (RWND) size from the receive device and then transmitting packets in a smaller size than that. The transmit device may fulfill congestion control by monitoring the condition of the network and adjusting the congestion window (CWND) size based on a result monitored. The CWND size adjusted may determine the size of one packet of transmission.
The transmit device supportive of flow control and congestion control may determine the size of one packet of transmission using the smaller of the RWND size and the CWND size.
For congestion control purposes, the transmit device may predict the condition of the network based on information provided from the receive device or by directly monitoring the condition of the network.
For example, the transmit device may predict the condition of the network based on the reception of a notification indicating the failure to receive a particular packet from the receive device or failure to receive a response signal (e.g., an ACK) from the receive device within a predetermined time period. Upon failure to receive a response signal (e.g., an ACK) from the receive device within a predetermined time period, the transmit device may be subject to a time-out. The transmit device may notice the failure of the receive device to receive a particular packet by receiving a duplicate ack (DUP-ACK) from the receive device. That is, the transmit device may recognize the occurrence of a packet loss.
Typically, when a time-out occurs, the transmit device adjusts the CWND size based on TCP congestion control, taking it long to recover the transmit bandwidth. This is why, as per the TCP congestion control, the CWND size sharply reduces when an error occurs, but on recovery, the increase in the CWND size is relatively slow. Further, as the period of retransmission attempted after the time-out occurs exponentially increases, a delay may intervene between when the error recovers and when the transmission resumes.
This leads to the need for preparing for schemes for enabling the transmission to resume earlier upon error recovery after a time-out and shortening the time for recovering a desired transmission speed after the transmission resumes.
The above information is presented as background information only to assist with an understanding of the present disclosure. No determination has been made, and no assertion is made, as to whether any of the above might be applicable as prior art with regard to the present disclosure.